1. Field of the Invention
The present invention relates to an optical waveguide apparatus that includes an optical waveguide, such as an optical waveguide sheet, apparatuses using the optical waveguide apparatus, and a method for making the optical waveguide apparatus. As disclosed herein, the optical waveguide sheet or the optical sheet is a waveguide that permits, for example, an optical transmission from a light-transmitting unit that is not directed at a light-receiving unit, as well as an optical transmission from the light-transmitting unit to the light-receiving unit.
2. Description of the Related Background Art
In recent years, performance of portable equipment, such as personal computers, cellular phones and personal digital assistants (PDAs), and digital audio-visual devices, significantly improved. Different means for interconnecting this equipment are being developed using all kinds of frequency bands in both wireless and wire forms. Therefore, appropriate and prompt ways are needed to cope with malfunctions of digital equipment due to electromagnetic interference from electrical substrates (electromagnetic interference: EMI), external electrical waves (resistance), and signal errors resulting from defective connections (signal integrity (SI)). In view of these electromagnetic wave problems, products prior to shipment are required to meet the standards prescribed by the Radio Law. Development costs for taking these measures continuously increase. In this situation, the optical wiring or interconnection without any electromagnetic induction is expected to radically solve the above regulatory and technical problems.
Further, in the near future, high-speed interconnections will undoubtedly be incorporated into homes. Hence, there is a need to prevent the malfunctions and noise intervention even when high-speed electronic equipment is freely connected in a variety of ground environments. Also, in this respect, the optical interconnection is an effective means that can readily achieve an electrical isolation from the ground.
Various methods for the optical interconnections have been proposed. FIG. 1 illustrates an optical wiring structure 1100 disclosed in Japanese Patent Application Laid-Open No. 9(1997)-270751. In FIG. 1, reference numeral 1120 designates an electrical circuit board. Reference numeral 1130 designates an emitting end of optical signals S1, S2 and S3. Reference numeral 1133 designates an optical-signal input portion. Reference numeral 1101 designates an optical bus (optical sheet). Reference numeral 1134 designates an optical-signal output portion. Reference numeral 1140 designates a receiving end of optical signals S1, S2 and S3. Optical devices 1132 and 1142 driven by driver circuits 1131 and 1141 are mounted at the output and input ports 1130 and 1140, respectively. The optical device 1132 is optically coupled to the optical sheet 1101 through a 45-degree mirror (optical-path converting unit) 1133s. 
In the structure of FIG. 1, the positioning or alignment between the optical device 1132 and the optical bus (optical sheet) 1101, more specifically, between the optical device 1132 and the mirror 1133s, is critically important in coupling light from the optical device 1132 to the optical bus 1101.